Question

if the following quantities are in proportion find the value of X 7, 21 and x​

Answer 1

](vii) 7 : 21 : x : 45

⇒ 21 × x = 7 × 45

⇒ x = (7 × 45)/21 = 45/3 = 15.

Answer 2

Answer:

We will learn how to solve word problems using proportion. If four numbers p, q, r and s are in proportion, then p and s are called the extreme terms and q and r are called the middle terms. Then, the product of extreme terms (i.e. p × s) is equal to the product of middle terms (i.e. r × s).

Therefore, p : q : : r : s ⇒ ps = qr

Solved problems using proportion:

1. Determine if the following are in proportion. If yes write them in proper form.

(i) 32, 48, 140, 210; (ii) 6, 9, 10 and 16

Solution:

(i) 32, 48, 140, 210

32 : 48 = 32/48 = 2/3 = 2 : 3

140 : 210 = 140/210 = 2/3 = 2 : 3

So, 32 : 48 = 140 : 210

Therefore, 32, 48, 140, 210 are in proportion.

i.e., 32 : 48 :: 140